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arxiv: 2604.11727 · v1 · submitted 2026-04-13 · ⚛️ physics.ins-det · hep-ex

Characterization of the 20-inch Photomultiplier Tubes for RENE Detector

Junkyo Oh , Byeongsu Yang , Cheong Heo , Daeun Jung , Dong Ho Moon , Eungyu Yun , Hyun Woo Park , Jae Sik Lee
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Jisu Park Ji Young Choi Kyung Kwang Joo Ryeong Gyoon Park Sang Yong Kim Sunkyu Lee Insung Yeo Myoung Youl Pac Jee-Seung Jang Eun-Joo Kim Hyunho Hwang Junghwan Goh Wonsang Hwang Jiwon Ryu Jungsic Park Kyu Jung Bae SeoBeom Hong Hyunsoo Kim Dojin Kim Jonghee Yoo Seunghwan Choi Wonjun Lee Jubin Park Myung-Ki Cheoun Intae Yu
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Pith reviewed 2026-05-10 15:57 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-ex
keywords photomultiplier tubesR12860 PMTRENE detectorgain non-uniformitylate pulsesafterpulsesneutrino detectionreactor antineutrino anomaly
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The pith

Two 20-inch PMTs for the RENE detector exhibit measured gain non-uniformity from their photocathode and dynode structure plus quantified late and afterpulse behaviors.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines the performance of two 20-inch Hamamatsu R12860 photomultiplier tubes planned for the RENE liquid scintillation detector, which aims to address the reactor antineutrino anomaly. It measures charge and timing responses at nominal and target gains, focusing on gain non-uniformity from the large photocathode and box-and-line dynode structure. The study also details the rates, timing, and charge distributions of late pulses and afterpulses. These characterizations are crucial for correctly interpreting detector signals and estimating systematic uncertainties in neutrino experiments.

Core claim

The authors characterize the R12860 PMT by evaluating charge and timing responses at nominal and target gains, measuring the maximum gain variation arising from the large-diameter photocathode with box-and-line dynode structure, and investigating the occurrence rate, timing, and charge distributions of late pulses and afterpulses.

What carries the argument

The box-and-line dynode structure combined with a large-diameter photocathode, which produces gain non-uniformity, together with timing and charge distribution measurements that quantify late pulses and afterpulses at operational gains.

If this is right

  • The results will aid in the interpretation of signals from the RENE detector.
  • They serve as a reference for estimating potential systematic uncertainties in RENE data.
  • The findings provide valuable information for other experiments employing the same type of PMTs.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Unaccounted gain non-uniformity across the full PMT array could broaden the energy resolution of the RENE detector beyond current estimates.
  • Similar late-pulse and afterpulse corrections may be needed in other large liquid-scintillator neutrino detectors using 20-inch box-and-line PMTs.

Load-bearing premise

The performance of the two tested PMTs is representative of all units to be installed in the RENE detector and laboratory conditions match actual operational conditions.

What would settle it

Measurements on additional R12860 PMTs showing substantially larger gain variations or different late-pulse and afterpulse rates and distributions would indicate the tested pair is not representative.

Figures

Figures reproduced from arXiv: 2604.11727 by Byeongsu Yang, Cheong Heo, Daeun Jung, Dojin Kim, Dong Ho Moon, Eungyu Yun, Eun-Joo Kim, Hyunho Hwang, Hyunsoo Kim, Hyun Woo Park, Insung Yeo, Intae Yu, Jae Sik Lee, Jee-Seung Jang, Jisu Park, Jiwon Ryu, Ji Young Choi, Jonghee Yoo, Jubin Park, Junghwan Goh, Jungsic Park, Junkyo Oh, Kyu Jung Bae, Kyung Kwang Joo, Myoung Youl Pac, Myung-Ki Cheoun, Ryeong Gyoon Park, Sang Yong Kim, SeoBeom Hong, Seunghwan Choi, Sunkyu Lee, Wonjun Lee, Wonsang Hwang.

Figure 1
Figure 1. Figure 1: Schematic drawing of the RENE detector (top view). PMTs ar [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Structure of venetian blind dynode system in R3600 (left) an [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Schematic diagram for the test setup. charge distributions for the two PMTs under single-photon illumination. The pedestal, SPE, and 2 p.e. distributions were determined by fitting the charge distribution with Gaussian and error functions. The flat components between the pedestal and SPE distribution, modeled by an error function, can arise from processes such as photons passing through the photocathode an… view at source ↗
Figure 4
Figure 4. Figure 4: Typical pulse shapes for the two PMTs in response to picosec [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Charge distributions of the PMT signals. The pedestal, SPE an [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: TTS measured using SPE signals at 1 × 107 gain. The red trend line represents the convolution of a Gaussian and an exponential function: f(t) = A 2τ exp  σ 2 2τ 2 − t−µ τ  erfc  √σ 2τ − t−µ √ 2σ  . power-law relationship, G(V ) = α × V β . Here, α reflects intrinsic properties determined by the PMT’s geometric configuration and materials, serving as a proportional constant that sets the overall gain. M… view at source ↗
Figure 7
Figure 7. Figure 7: Gain as a function of applied voltage. The results follow the pow [PITH_FULL_IMAGE:figures/full_fig_p009_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Stability of the mean SPE charge at 1680 V for PMT A and 1650 V [PITH_FULL_IMAGE:figures/full_fig_p009_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: (a) Outline and dimensions of the R12860 PMTs [14]. (b) X and Y c [PITH_FULL_IMAGE:figures/full_fig_p010_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: The relative gain for each PMT. Measured values are normaliz [PITH_FULL_IMAGE:figures/full_fig_p011_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: TTS as a function of the applied voltage. [PITH_FULL_IMAGE:figures/full_fig_p012_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: Timing distribution for each PMT. Late pulses clearly appear a [PITH_FULL_IMAGE:figures/full_fig_p012_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: Accumulated pulses for 60 µsec at various light intensities for PMT A. The inset figures present zoomed-in views of the afterpulses with red dotted lines indicating the 150 mV level. 14 [PITH_FULL_IMAGE:figures/full_fig_p014_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: Accumulated pulses for 60 µsec by the various light intensities for PMT B. The inset panels provide zoomed-in views of the afterpulses with red dotted lines indicating the 150 mV level. 15 [PITH_FULL_IMAGE:figures/full_fig_p015_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: Representative plots of the charge versus time for all puls [PITH_FULL_IMAGE:figures/full_fig_p016_15.png] view at source ↗
Figure 16
Figure 16. Figure 16: Event rate as a function of event time for PMT A (left) and P [PITH_FULL_IMAGE:figures/full_fig_p016_16.png] view at source ↗
Figure 17
Figure 17. Figure 17: Charge distributions of the afterpulses for PMT A. [PITH_FULL_IMAGE:figures/full_fig_p018_17.png] view at source ↗
Figure 18
Figure 18. Figure 18: Charge distributions of the afterpulses for PMT B. [PITH_FULL_IMAGE:figures/full_fig_p019_18.png] view at source ↗
Figure 19
Figure 19. Figure 19: Charge distributions of the afterpulses in the AP1 region wit [PITH_FULL_IMAGE:figures/full_fig_p020_19.png] view at source ↗
Figure 20
Figure 20. Figure 20: Charge distributions of the afterpulses in the AP1 region wit [PITH_FULL_IMAGE:figures/full_fig_p020_20.png] view at source ↗
read the original abstract

To address the Reactor Antineutrino Anomaly (RAA) observed in neutrino experiments, the Reactor Experiment for Neutrino and Exotics (RENE) has been initiated using a liquid scintillation detector. In this study, we investigate the characteristics of two 20-inch Hamamatsu R12860 photomultiplier tubes (PMTs) intended for installation in the RENE detector. The charge and timing responses of the PMTs were evaluated at both the nominal and target gains expected during actual operation. In particular, gain non-uniformity arising from the large-diameter photocathode with a box-and-line type dynode structure was examined, and the maximum gain variation was measured. The occurrence rate, timing, and charge distributions of late pulses and afterpulses were also investigated to characterize the specific response features of the R12860 PMT. The results reported in this study will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties in RENE data. Furthermore, these findings are expected to provide valuable information for other experiments employing the same type of PMTs.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript reports experimental characterization of two 20-inch Hamamatsu R12860 photomultiplier tubes intended for the RENE liquid-scintillator detector. It evaluates charge and timing responses at both nominal and target gains, quantifies maximum gain non-uniformity arising from the large photocathode and box-and-line dynode structure, and measures occurrence rates together with timing and charge distributions of late pulses and afterpulses. The authors present these data as a reference for interpreting RENE signals and estimating systematic uncertainties.

Significance. If the two tested units prove representative of the full production set, the reported gain-variation and pulse-characteristic data would supply a useful baseline for energy-scale calibration and background modeling in RENE and in other experiments employing the same PMT type. The work directly addresses a practical instrumentation need for the RENE program aimed at the Reactor Antineutrino Anomaly.

major comments (2)
  1. [Abstract] Abstract: the claim that the results from the two tested PMTs 'will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties' is load-bearing for the paper's stated purpose, yet no batch statistics, manufacturer QA comparisons, or discussion of unit-to-unit or photocathode-uniformity variations across the 20-inch diameter are provided. Without such evidence the reference values cannot be shown to be statistically representative of the full detector array.
  2. [Results (gain non-uniformity)] Results on gain non-uniformity: the maximum gain variation is presented as a key observable for the box-and-line dynode, but the manuscript supplies neither the number of sampled positions or events used to determine the maximum, nor the associated uncertainty or selection criteria. This prevents assessment of whether the quoted value is robust or sensitive to analysis choices.
minor comments (2)
  1. [Abstract] The abstract and introduction should state the numerical values of the nominal and target gains used in the measurements.
  2. [Figures] Figure captions and axis labels for timing and charge distributions should explicitly indicate the gain setting (nominal or target) to which each panel corresponds.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments, which help clarify the scope and robustness of our measurements on the two R12860 PMTs. We address each major comment below and will revise the manuscript accordingly.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the claim that the results from the two tested PMTs 'will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties' is load-bearing for the paper's stated purpose, yet no batch statistics, manufacturer QA comparisons, or discussion of unit-to-unit or photocathode-uniformity variations across the 20-inch diameter are provided. Without such evidence the reference values cannot be shown to be statistically representative of the full detector array.

    Authors: We agree that data from only two units cannot demonstrate statistical representativeness of the full production batch or detector array. The manuscript reports detailed characterization of these specific PMTs as initial reference measurements for RENE. We will revise the abstract to remove any implication of broad representativeness, stating instead that the results provide reference data from the tested units for signal interpretation and uncertainty estimation, while explicitly noting the limited sample size. No manufacturer QA batch statistics or unit-to-unit variation data are available to the authors. revision: yes

  2. Referee: [Results (gain non-uniformity)] Results on gain non-uniformity: the maximum gain variation is presented as a key observable for the box-and-line dynode, but the manuscript supplies neither the number of sampled positions or events used to determine the maximum, nor the associated uncertainty or selection criteria. This prevents assessment of whether the quoted value is robust or sensitive to analysis choices.

    Authors: The referee is correct that the original manuscript lacks these experimental details. In the revised version we will add a dedicated paragraph describing the gain non-uniformity scan: the number and spatial distribution of sampled positions on the photocathode, the number of events recorded per position, the precise definition and selection criteria used to identify the maximum variation, and the estimated uncertainty on the reported value. This will enable readers to assess robustness. revision: yes

Circularity Check

0 steps flagged

No circularity: direct experimental measurements only

full rationale

The manuscript reports laboratory measurements of charge/timing response, gain non-uniformity, late-pulse and afterpulse distributions on two specific R12860 PMTs at nominal and target gains. No equations, ansatzes, fitted parameters renamed as predictions, or derivation steps appear. The central statements are empirical observations presented as reference data for RENE; they do not reduce by construction to prior self-citations or to quantities defined in terms of the reported results themselves. The paper is therefore self-contained against external benchmarks and receives the default non-circularity finding.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the assumption that standard PMT testing protocols apply and that the two sampled tubes represent the production batch; no free parameters are fitted and no new entities are postulated.

axioms (1)
  • domain assumption Standard photomultiplier tube operation principles govern charge and timing responses in the R12860 model
    Invoked when interpreting gain non-uniformity and pulse timing data.

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